the history and philosophy of astronomy lecture 13: descartes. presentation

8/9/2019 The History and Philosophy of Astronomy Lecture 13: Descartes. Presentation

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The History and Philosophyof Astronomy

(Lecture 13: Descartes)

Instructor: Volker BrommTA: Jarrett Johnson

The University of Texas at Austin

Astronomy 350L

(Fall 2006)


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Rene Descartes: The First Modern Philosopher

1596 (La Haye) 1650 (Stockholm)

founder of modern philosophy- method of radical doubt- mind-body dualism

invented analytical geometry(Cartesian coordinates)

Importance for astronomy:

- mechanistic universe

- infinite universe


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Descartes: Geography of his Life


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School in La Fleche (1606-14)

newly established elite school, run by Jesuits Curriculum:

- Latin

- scholastic philosophy- state-of-the-art mathematics


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A Restless Early Life

1615- 16: University in Poitiers (law degree)

1618: joins Dutch army (as engineer)

1619: joins Bavarian army (30 Years War)

1622-28: lives in Paris

Also: extensive travel throughout this period


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Descartes in Paris (1622-28)

Paris: the hotspot of the Age!


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Descartes in Paris: Centralization of Power

Cardinal Richelieu (1585-1642)

- rise in power- becomes Chief Minister- creates centralized (abolutistic)

French State- founds Academie Francaise(guardian of French language)


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Descartes: A Desire for Calm and Peace

after having seen the

world, Descartes wants

quiet time to think andwrite

decides to leave bustleof Paris behind

move to Netherlands(sedentary 2nd half ofhis life)


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Descartes in the Netherlands (1628-49)

A young, vibrant nation: most tolerant place in Europe then!


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Descartes in the Netherlands (1628-49)

A superpower of the 17th century!


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The Philosopher: A New System

Discours de la Methode

(Discourse on the Method, 1637)

Radical doubt:- nothing is certain, but:

- Cogito, ergo sum

(I think, therefore I am)

Dualistic philosophy (mind-body)

First truly original philosophical

system since antiquity


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The Philosopher: Radical Doubt

Destruction of all previous certainties

I cannot be sure of what my senses tell me(after all, I could be dreaming)

But: I cannot doubt onething: That Idoubt (think)!

Thus: My thinking proves my existence!

I think, therefore I am!


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The Philosopher: Prove Gods Existence

I know that I am not perfect, but I have the

idea of a perfect being in my mind!

This perfect being cannot be the same as me,as I myself am surely imperfect!

This perfect being would not be perfect if it

did not also exist!

The perfect being (God) exists!


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Prove Existence of Outside Objects

In my thinking, I clearly conceive of objects in

the outside world!

God, being perfect, would not deceive me!

The outside world exists!

But this outside world is very different from

the thinking mind!

There are two kinds of substance!


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Cartesian Dualism

Mind Bodies

thinks has extension(length, breadth, width)

behave accordingto laws of physics

(determinism)

free thought/will

Two realms of reality are fundamentally differentand independent!


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Cartesian Dualism

The human body is a

machine

But the brain then is alsopart of this machine

Big Q: How does the

mind interact with the

brain?


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Mind-Body Interaction: Clock Analogy

Mind Brain

Mind and body only appear to interact, but arereally pre-set in parallelism!

What about free will? (Brain follows deterministiclaws)


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The Scientist: Matter in Motion

Principia Philosophiae

(Philosophical Principles, 1644)

Theory of matter, space,and motion

A mechanical system of

the universe (matter in motion)

An infinite universe


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The Scientist: Space and Matter

begin with empty (undressed) space of geometry!


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Direct collisions can change motion!


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Assume for the moment that there were empty space!

There can be no vacuum!

matter

Empty space

But: Portion of empty space has extension! Thus (according to Descartes): There must also

be matter (whatever has extension is matter,

and vice versa!)


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space is densely packed with material particles!

No gaps between! World is a plenum!


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Motion in Completely Filled Space

particle experiences pushes from adjacent particles!

path is bent into closed (~circular) shape!


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Descartes Model of the Universe

vortex (whirlpool) cosmology!

space/matter have no edge!

infinity of vortices- infinitude of Suns and

Solar systems

The universe has no center

and no edge!

Red path: Descartes (wrong) theory for comets!


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The Clockwork Universe

Descartes establishes picture of universe governedby simple laws of motion (the mechanical philosophy)

Many of detailed explanations were soon found to be wrong,but overall approach became highly influential (e.g., Newton)!


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Toward the Infinite Universe: Thomas Digges

popularizer of Copernican model (1576)!

stars are notconfined to a thin shell!


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1663: Descartes on Index of Forbidden Books

Index Librorum Prohibitorum

Organized censorship

Introduced in 1559

Abolished in 1966


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Journeys end: Move to Stockholm

Invitation from QueenChristina of Sweden

Descartes as Queens

private tutor

Problem: Descarteshas to show up at court

already at 5am


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Journeys end: Death in Stockholm 1650

contracts lethal pneumonia during fierce Swedish winter!

D t


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Descartes

Rene Descartes:- founder of modern philosophy

- a new system of philosophy

- based on method of radical doubt (Cogito ergo sum)

Cartesian Dualism

- mind vs matter- Q: How can the brain be influenced by the mind/soul???

Cartesian model of the universe- consists of vortices (matter in motion)

- universe is infinite

- universe is governed by mechanical laws

the history and philosophy of astronomy lecture 13: descartes. presentation

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